1. Field of the Invention
The present invention relates to a pixel structure, especially to a charge-sharing type pixel structure.
2. Description of the Related Art
Thin-film transistor LCD is one type of liquid crystal display device. Because of having advantages of high resolution, low power consumption, light weight and variety of sizes, thin-film transistor LCD has been widely used in the field of liquid crystal display device.
Large sized thin-film transistor LCD has a view angle problem, that is, when a user watch the screen of the LCD with different angles, the screen has different brightness and contrast. Nowadays, in order to improve the shortcoming of poor view angle of thin-film transistor LCD, manufacturers has disclosed various wide viewing angle technologies, such as multi-domain vertical alignment (MVA) technology, which effectively increase the viewing angle of the display device. However, although the MVA technology can improve viewing angle problem, a color-washout problem occurred at oblique viewing angles remains to be solved.
In order to harmonize the colors at oblique viewing angles and a vertical viewing angle, manufacturers has provided a charge-share pixel structure. As shown in FIG. 1, a charge-share pixel structure 9 is to divide a pixel into a first sub-pixel 90 and a second sub-pixel 91, wherein the first sub-pixel 90 has a first thin-film transistor TFT1 that is connected to a first gate line Gn, a second thin-film transistor TFT2 that is connected to the first gate line Gn, and a voltage-dividing thin-film transistor TFTS that is connected to the second thin-film transistor TFT2 and a second gate line Gn+1. When the first thin-film transitor TFT1 and the second thin-film transistor TFT2 are simultaneously switched on by the first gate line Gn, a liquid crystal capacitor Clc1 of the first sub-pixel 90 and a liquid crystal capacitor Clc2 of the second sub-pixel 91 have the same gray scale voltage. Subsequently, the voltage-dividing thin-film transistor TFTS is switched on by the second gate line Gn+1. Because charges are shared between the liquid crystal capacitor Clc1 of the first sub-pixel 90 and other voltage-dividing capacitors Ca, Cb, the liquid crystal capacitor Clc1 of the first sub-pixel 90 then has a gray scale voltage that is different from the gray scale voltage of the liquid crystal capacitor Clc2 of the second sub-pixel 91, and thereby improves color-washout phenomenon at oblique viewing angles.
However, for such design of the aforementioned charge-sharing pixel structure, once the mask pattern for forming the voltage-dividing capacitors and the voltage-dividing thin-film transistor is determined, division of gray scale voltage can not be re-adjusted except modifying the mask pattern, which lacks of flexibility.
Therefore, it is necessary to provide a charge-sharing type pixel structure to overcome the problems existing in the conventional technology.